“Balancing considerations regarding the unpredictability of timing of onset of the influenza season and concerns that vaccine-induced immunity might wane over the course of a season, it is recommended that vaccination should be offered by the end of October.”
Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices — United States, 2019–20 Influenza Season
While we now think that flu vaccines are delayed if we don’t start seeing them in August, it is important to remember that it wasn’t that long ago that experts recommended that the optimal time to get a flu vaccination was in October and November.
It wasn’t until the 2006-07 flu season that we started to get updated guidelines for earlier flu vaccinations, starting with recommendations to offer flu shots in September for high risk groups “to avoid missed opportunities for vaccination.”
The next year the recommendation for the timing of flu vaccination became “health-care providers should begin offering vaccination soon after vaccine becomes available and if possible by October. To avoid missed opportunities for vaccination, providers should offer vaccination during routine health-care visits or during hospitalizations whenever vaccine is available.”
And with over 150 million doses of flu vaccine produced each year, it has been some time since we have seen a true flu vaccine shortage. The fact that more and more companies are making flu vaccines also helps ensure that shortages don’t happen.
Still, most flu vaccine manufacturers use older egg-based technology to grow flu virus strains for vaccine, which is not as reliable or flexible as many would wish it to be. This is what often leads to flu vaccine delays and shortages – the fact that in some years, the flu virus is simply hard to grow.
Flu Vaccine Delays and Shortages
How common are flu vaccine delays or shortages?
A flu vaccine delay and shortage in 2000 caused a supply of only 26.6 million doses of flu vaccine by October (vs about 76 million the previous year) and about 8 million fewer doses by the end of the season. The delay and shortage was caused by manufacturers having difficulty growing the H3N3 strain of flu and one fewer flu vaccine manufacturer.
In 2004, Chiron Corporation had its license suspended in the United Kingdom because of ‘concerns of possible microbial contamination of product.’ Chiron was to produce between 46-48 million doses of influenza vaccine for the United States and so overnight, we had our flu vaccine supply cut in half, leading to true shortages. An allocation plan that year helped to make sure that flu vaccine got to high-priority providers and people who needed them though.
In 2006, there was a delay in getting flu shots for younger children until November, as Sanofi Pasteur had difficulty producing their flu shots because of poor growth of one of the strains of influenza in the flu shot.
The emergence of H1N1 pandemic strain of influenza led to shortages in 2009. The problem that year was one of timing. The H1N1 flu virus was discovered just as seasonal flu vaccine was starting to be made, which led to a shift in priorities for flu vaccine production. The biggest problem, in addition to a slow growing H1N1 virus for the vaccine, was an early start to the flu season though. When H1N1 vaccine became available in October, it was too late for most people – flu season had already peaked.
After the 2009 H1N1 pandemic, we had several years of a more than ample supply of flu vaccine and on time delivery of our flu vaccine, which likely got most of us spoiled. It also was why we were all surprised by the production problems that led both GSK and Sanofi to have delays in shipping their flu vaccine in 2014.
We also had some flu vaccine delays in 2015. That year, MedImmune, the manufacturers of FluMist were supplying over 16 million doses of flu vaccine, but stated that “We expect customers will begin receiving product in early September and we will continue delivering vaccine throughout the season.”
Sanofi Pasteur also reported problems in 2015, stating that “Multidose vial orders are anticipated to be filled by the end of September; single use syringes will be supplied at a steady pace through November.”
2019-20 Flu Season Supply
Unfortunately, there will be some delays this flu season too, likely caused by a late update to the H3N2 strain because of drifting.
“Two strain changes coupled with the late decision for the H3N2 strain from VRBPAC, due to the drift that was being seen in surveillance was the issue. At least right now, capacity is all right with injectable vaccine.”
Remember, the WHO and FDA, via the Vaccines and Related Biological Products Advisory Committee (VRBPAC), made late decisions on which H3N2 strain to include in the 2019-20 flu vaccines.
So it shouldn’t be a surprise that pediatricians are getting notices that they will only receive a small part of their order of FluMist from AstraZeneca this year.
Or that Sanofi Pasteur, which will produce 40% of this year’s projected supply, is reporting a 4 to 6 week delay.
Even if word is just now trickling down to pediatricians, others have known about these delays for months…
Luckily, unlike delays in some other years, this doesn’t mean any shortages of flu vaccine. It is just that some doctors and clinics won’t be getting their first shipments as early as they would have liked. And not everyone will be able to get FluMist, if that is their preference.
Still, there will be a lot of flu vaccine and plenty of time to get everyone vaccinated and protected well before flu season hits!
What You Need to Know about Flu Vaccine Delays and Shortages
Other things to know about flu vaccine delays and shortages include that:
Pharmacies often seem to get their shipment of flu vaccine before pediatricians do, especially when there is any kind of delay.
Since even in a typical year, flu vaccine for the Vaccine for Children’s program gets to pediatricians a few weeks after other flu vaccine, this stock will likely also be delayed this year.
While they can certainly be frustrating, a flu vaccine delay shouldn’t mean that your family can’t get a flu vaccine.
Tamiflu can be an alternative to the flu shot for some high risk children who haven’t been vaccinated yet.
If there is a flu vaccine delay or shortage and your child is in a high risk group for complications from the flu, get a flu vaccine as soon as you can, wherever you can, and be sure you pediatrician puts you on a high priority list to get any vaccine that becomes available.
As this infographic describes, it really isn’t that complicated…
What Does Vaccine Shedding Really Mean?
To clear up some things:
yes, some vaccines do actually shed, but it is rarely a reason to avoid getting vaccinated and protected
of the vaccines that we use routinely, shedding is limited to the rotavirus vaccines, FluMist, and the chickenpox vaccines
some other vaccines that can shed include the oral polio vaccine and the smallpox vaccine
the rubella component of MMR may very rarely shed, but only in breastmilk
If vaccines do shed, why shouldn’t we be more concerned about it?
Well, for one thing, most vaccines don’t shed.
DTaP, hepatitis A, hepatitis B, Hib, flu, IPV, HPV, meningococcal, pneumococcal, and Tdap shots – none of them shed.
And then there is the fact that:
when a vaccine sheds, it is the weakened or attenuated vaccine strain, not the wild strain that would cause more serious disease. Putting it another way, if the vaccine strain doesn’t make the person who is getting immunized sick, then why would it get someone else sick if they got it through shedding? Of course, there is a situation in which even a vaccine strain could be dangerous, and that’s for those who are severely immunosuppressed. Still, natural disease would be bad for these kids too!
even with oral polio vaccines, the problem isn’t really shedding, which actually provides a type of passive immunization in areas where polio is still not well controlled. The problem is that very rarely, the attenuated virus in the oral polio vaccine can revert to a form that can cause the person who was vaccinated to actually develop polio (VAPP). Now, shedding of this strain would be a problem, but only if the other person wasn’t immune.
rotavirus vaccines only shed in stool. You can avoid it by washing your hands when you change your child’s diapers, which you hopefully do anyway.
FluMist is attenuated and cold-adapted, which means that it won’t replicate well in our warmer nasal passages and respiratory tracts.
you have to actually get a rash, which is rare, for the chickenpox vaccine to shed.
it is only kids with eczema that usually get sick if they are exposed to someone who recently had the smallpox vaccine. Since the smallpox vaccine causes skin reactions, even the attenuated vaccine strain can cause severe reactions if a child’s skin is already broken down, like with eczema.
Are you still concerned about shedding?
Can a Vaccinated Person Transmit Measles Through Shedding?
To put your mind at ease, understand that you are not going to get measles from shedding.
“In this systematic review, we have determined that there have been no confirmed cases of human-to-human transmission of the measles vaccine virus.”
Greenwood et al on A systematic review of human-to-human transmission of measles vaccine virus
If you aren’t vaccinated and protected, you could easily get it from someone who has measles and who is shedding the wild type virus though. Measles is so contagious, you just have to be in the same room as someone with measles and you will likely get sick. In fact, you can enter a room a few hours after they have left and sill catch measles!
And in theory, if someone developed vaccine-associated measles – they got sick with a vaccine-strain of measles after getting vaccinated – then they could spread the virus to someone who wasn’t immune. That’s just because they would be contagious though, not anything specific to vaccines and shedding. Also, it is basically unheard of for this to happen.
They aren’t even people with measles. Instead, they typically have a vaccine reaction, a rash and/or fever after getting their MMR and they test positive for the vaccine strain of measles because they just got a live virus vaccine.
Is Vaccine Shedding a Threat?
Shedding isn’t the threat that anti-vaccine folks make it out to me.
Think about it. If it really was a big problem, then why don’t more intentionally unvaccinated kids with exemptions get sick when they are around kids who are vaccinated?
“Health officials should require a two-week quarantine of all children and adults who receive vaccinations. This is the minimum amount of time required to prevent transmission of infectious diseases to the rest of the population, including individuals who have been previously vaccinated.”
Sally Fallon Morell, president of the Weston A. Price Foundation
We don’t actually quarantine anyone after they are vaccinated, so why don’t more kids with immune system problems get sick via shedding?
Or just think about what happens in a typical daycare or school. All of the kids don’t get vaccinated on the same day, so if shedding was an issue, wouldn’t the kids who had gotten their vaccines first shed on the ones who weren’t yet vaccinated, getting them sick?
Of course, this doesn’t happen. Again, shedding isn’t the threat that anti-vaccine folks make it out to be.